DESCRIPTION (Adapted from applicant's description): In the normal course of development at around the end of the first year of life, human infants respond to a change in an adult's alignment of gaze by turning in the same direction as if to see where the adult is looking. This phenomenon, known as joint attention, is believed to play an important role in referential communication. Deficits in joint attention have also been associated with autism. Using computerized displays of real faces, the investigators have demonstrated in pilot work that infants as young as 3 months are sensitive to eye gaze and that this influences their orienting behavior to peripheral probes. This research proposal will follow on from this pilot work with a set of experiments to determine why orienting to eye gaze is so elusive in young infants, what is the effect of dissociating eye and head movements, and, finally, what is the contextual role of the face in gaze monitoring?